S. Troliermckinstry et J. Koh, COMPOSITION PROFILING OF GRADED DIELECTRIC FUNCTION MATERIALS BY SPECTROSCOPIC ELLIPSOMETRY, Thin solid films, 313, 1998, pp. 389-393
In this work, the characterization of graded composition layers in tra
nsparent materials by spectroscopic ellipsometry (SE) is described. Th
e sensitivity limits were modeled by comparing calculated spectra for
samples with and without diffusion profiles at the sample surface for
several glass compositions. It was found that for known index profile
shapes, the depth sensitivity can be quite high. The sensitivity of th
e technique increases as the diffusion depth and refractive index cont
rast increases. The accuracy of the thickness determination depends on
the total thickness of the graded layer; for a given system, the accu
racy of the composition measurements did not depend on the surface con
centration. Leached alkali-aluminosilicate and modified lead silicate
glasses were examined by SE to experimentally confirm the modeling pre
dictions on the composition depth profiling. Extremely good correlatio
n between the SE-determined depth profile and SIMS measurements on sim
ilar samples was obtained for the case of the modified lead silicate g
lass. For the aluminosilicate glass, simultaneous roughening of the gl
ass surface during etching makes composition profiling more difficult.
(C) 1998 Elsevier Science S.A.